#pragma GCC optimize ("O2")
#pragma GCC target ("avx2")
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define Would
#define you
#define please

const int SZ = 300000;
class UF {
public:
	int P[SZ + 1];
	UF() : P() {
		rep1(i, SZ) P[i] = -1;
	}
	int find(int A) {
		if (P[A] < 0) return A;
		return P[A] = find(P[A]);
	}
	bool unite(int A, int B) {
		int a = find(A);
		int b = find(B);
		if (a == b) return false;
		if (P[a] > P[b]) swap(a, b);
		P[a] += P[b];
		P[b] = a;
		return true;
	}
} uf;

const int mod = 1e9 + 7;
constexpr ll modpow(ll A, ll B) {
	ll kotae = 1;
	while (B > 0) {
		if (B & 1) kotae = kotae * A % mod;
		A = A * A % mod;
		B >>= 1;
	}
	return kotae;
}

vector<pair<int,int> > E[200001];
ll kotae = 0;
int N, M, X;
int dfs(int u, int mae) {
	int ret = 1;
	for (auto p : E[u]) {
		int to = p.first;
		if (mae != to) {
			ll tmp = dfs(to, u);
			kotae += tmp * (N - tmp) % mod * modpow(X, p.second) % mod;
			ret += tmp;
		}
	}
	return ret;
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	cin >> N >> M >> X;

	int x[200001], y[200001], z[200001];
	rep1(i, M) {
		cin >> x[i] >> y[i] >> z[i];

		if (uf.unite(x[i], y[i])) {
			E[x[i]].pb({ y[i], z[i] });
			E[y[i]].pb({ x[i], z[i] });
		}
	}

	dfs(1, -1);

	co(kotae% mod);


	Would you please return 0;
}